Effects of prenatal testosterone on sex and age differences in behavior elicited by stimulus pups in the rat.

Abstract

From Days 14 to 19, pregnant Wistar rats were treated with either 2 mg of testosterone propionate (TP) or vehicle. Thirty-, 60-, and 90-day-old offspring were tested individually during 15 min daily on 4 days with a stimulus litter, and pup-oriented and non-pup-oriented behaviors were recorded. Sex differences in pup-oriented behaviors observed in oil groups were eliminated by TP treatment, which affected mainly females. Additionally, TP treatment increased the frequency of self-grooming and decreased the time spent near the pups and the frequency of sniffing and pawing only at 90-days of age. Hiding behavior only occurred at 30 days of age, while pawing near the pups and lying-down behavior was observed mainly in adults. Results show that sex differences in behavior are present before subjects become sensitized to show evident maternal behavior, and suggest that prenatal androgens play an important role in the manifestation of these sex differences and that its effects depend on developmental factors.